This project seeks to extend current views of the functional organization of the primate somatosensory cerebral cortex and to identify the contributions of each of the multiple afferent pathways which project to the cortex. Electrophysiological and computer-aided neural data analysis techniques are employed to characterize the responses elicited from individual cerebral cortical neurons by the application of somatosensory stimuli in normal animals as well as in animals previously subjected to spinal tractotomies. It is anticipated that these data will provide a model enabling a mechanistic interpretation of the perceptual distortions resulting from neurological damage due to trauma or disease.